Precise connections established between two auditory brainstem nuclei, nucleus magnocellularis (NM) and nucleus laminaris (NL) are instrumental in conferring time coding in the mature chicken. NM and NL cells are generated from distinct rhombomeric regions in the chick embryo. During development, these cells coalesce within the auditory anlage prior to migrating to their mature hindbrain positions. Given that NM cells synapse onto NL neurons at maturity, the current proposal is designed to test specific hypotheses regarding interactions of NM and NL cells within the auditory anlage. Following rhombomere labeling, cells that give rise to NM and NL neurons can be visualized during migration to mature positions in the hindbrain. During this migratory process, cells will be assessed for functional development of membrane properties. In addition, cell coupling between cells of the same nucleus (e.g. NM to NM) or heterotypic coupling (e.g. NM to NL) will be investigated. The components mediating this communication will be identified and disrupted by gene transfection to investigate the role of cell coupling on migration patterns of these neurons. The proposed studies will provide integral information toward understanding the role of the auditory anlage in the development of these brainstem nuclei.